(a) Field of the Invention
The present invention relates to solder deposition methods, and more particularly to a solder deposition method by which solder is punched onto the solder joints of circuit elements.
(b) Description of the Prior Art
In the prior art, integrated circuit elements are mounted on a circuit board by the method of BGA (ball grid array), in which the solder joints of the integrated circuit elements are firstly applied with a layer of solder binder. Solder balls are then attached to the solder joints by the adhesive effect of the solder binder. The circuit board with the integrated circuit elements attached with solder balls is heated at a high time temperature, which melts the solder balls so that the solder is substantially attached on the solder joints. To assure that each solder joint of the circuit elements is in conductive contact with the circuit board, the solder balls each have to cover a large enough area after being melted, which requires high uniformity in the size and the shape of the solder balls. This is a disadvantage of the deposition method using solder balls, since the storage and transportation of the solder balls consume much more time, and the production cost is high.